%D \module
%D   [       file=mptopdf,
%D        version=2000.03.27,
%D          title=\METAPOST,
%D       subtitle=conversion to \PDF,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

%D The file \type {mptopdf} provides a quick way to convert
%D \METAPOST\ files to \PDF\ using a slightly stripped down
%D plain \TEX, \PDFTEX, and a few \CONTEXT\ modules.
%D
%D First generate a format, which in \WEBC\ looks like:
%D
%D \starttyping
%D pdftex --ini mptopdf
%D \stoptyping
%D
%D or:
%D
%D \starttyping
%D texexec --make --tex=pdftex --format=mptopdf --alone
%D \stoptyping
%D
%D Since this conversion only works with \PDFTEX\ or \PDFETEX,
%D the session is aborted when another \TEX\ is used. When
%D finished, the resulting \type {fmt} file should be moved to
%D the right location.
%D
%D The conversion itself is accomplished by:
%D
%D \starttyping
%D pdftex &mptopdf \relax filename.number
%D \stoptyping
%D
%D The \type {\relax} is needed since we don't want to process
%D the file directly. Instead we pick up the filename using
%D \type {\everypar}. Since this file is still the first one
%D we load, although delayed, the jobname is as we expect. So,
%D at least in \WEBC, the result of the conversion comes
%D available in the file \type {filename.pdf}. This conversion
%D process is roughly compatible with:
%D
%D \starttyping
%D texexec --pdf --fig=c --result=filename filename.number
%D \stoptyping
%D
%D This uses \CONTEXT, and is therefore slower. Therefore,
%D we provide a small \PERL\ script that does a faster job,
%D using the minimal format. Given that a format is
%D generated, one can say:
%D
%D \starttyping
%D mptopdf somefile
%D mptopdf somefile.123
%D mptopdf mp*.*
%D \stoptyping
%D
%D The results are copied into files named \type
%D {somefile-number}. This mechanism will also be available
%D in a next release of \TEXUTIL.

%D The \TEX\ implementation is rather simple, since we use some
%D generic \CONTEXT\ modules. Because we need a few register
%D allocation macros, we preload plain \TEX. We don't load
%D fonts yet.

\input syst-tex.mkii

%D We check for the usage of \PDFTEX, and quit if another
%D \TEX\ is used.

\ifx\pdfoutput\undefined
  \message{Sorry, you should use pdf(e)TeX instead.}
  \expandafter \endinput
\fi

%D The conversion to \PDF\ is carried out by macros, that
%D are collected in the file:

\input supp-mis.mkii
\input supp-pdf.mkii
\input supp-mpe.mkii  \MPcmykcolorstrue \MPspotcolorstrue

%D We use no output routine.

\output{}

%D Since we need to calculate and set the bounding box,
%D we definitely don't want to indent paragraphs.

\parindent=0pt

%D We use \type {\everypar} to pick up the filename and
%D process the \METAPOST\ graphic.

\everypar{\processMPfile}

%D The main macro shows a few \PDFTEX\ primitives. The main
%D work is done by the macro \type {\convertMPtoPDF} which is
%D defined in \type supp-pdf}. This macro interprets the
%D \METAPOST\ file. Close reading of this macro will probably
%D learn a few (\PDF) tricks. Apart from some path
%D transformations, which are needed since \PDF\ has a
%D different vision on paths, the graphic is positioned in
%D such a way that accuracy in \PDF\ xforms is guaranteed.

\def\processMPfile#1 %
  {\pdfoutput=1
   \pdfpkresolution600
   \pdfcompresslevel=9
   \chardef\makeMPintoPDFobject=1
   \hsize=100in
   \vsize=\hsize
   \hoffset=-1in
   \voffset=\hoffset
   \topskip=0pt
   \setbox0=\vbox{\convertMPtoPDF{#1}{1}{1}}%
   \ifdim\wd0<1in \message{[warning: the width  is less than 1in]}\fi
   \ifdim\ht0<1in \message{[warning: the height is less than 1in]}\fi
   \pdfpageheight=\ht0
   \pdfpagewidth=\wd0
   \box0
   \bye}

%D The \type {\chardef} forces the converter to build a so
%D called xform object. This is needed in case the graphic
%D uses special trickery, like shading.

%D Since \ACROBAT\ has troubles with figures smaller than
%D 1~inch, we issue a warning. When embedding graphics in
%D documents, a size less that 1~inch does not harm. In
%D order to overload runtime directives in the \PDFTEX\
%D configuration file, we set the offsets and output method
%D in the macro.
%D
%D The resulting \PDF\ file is about as efficient as such a
%D self contained file can be. However, if needed, this \PDF\
%D file can be converted to \EPS\ using for instance the
%D \PDFTOPS\ program (in \WEBC) or \GHOSTSCRIPT.

%D A few helpers:

{\catcode`\.=12
 \catcode`\p=12
 \catcode`\t=12
 \gdef\WITHOUTPT#1pt{#1}}

\def\withoutpt#1%
  {\expandafter\WITHOUTPT#1}

\def\negatecolorcomponent#1% #1 = \macro
  {\scratchdimen1pt\advance\scratchdimen-#1\onepoint
   \ifdim\scratchdimen<\zeropoint\scratchdimen\zeropoint\fi
   \edef#1{\withoutpt\the\scratchdimen}}

\let\negatedcolorcomponent\firstofoneargument

\def\negatedcolorcomponent#1%
  {\ifdim\dimexpr1pt-#1pt\relax<\zeropoint
     0pt%
   \else
     \expandafter\withoutpt\the\dimexpr1pt-#1pt\relax
   \fi}

\def\negatecolorcomponent#1% #1 = \macro
  {\edef#1{\negatedcolorcomponent{#1}}}

\countdef\realpageno=0 % to satisfy mkiv status reports

\dump
